New historic sea ice minimum

Today, the Northern Hemisphere sea ice area broke the record for the lowest recorded ice area in recorded history. The new record came a full month before the historic summer minimum typically occurs. There is still a month or more of melt likely this year. It is therefore almost certain that the previous 2005 record will be annihilated by the final 2007 annual minima closer to the end of this summer.

In previous record sea ice minima years, ice area anomalies were confined to certain sectors (N. Atlantic, Beaufort/Bering Sea, etc). The character of 2007’s sea ice melt is unique in that it is dramatic and covers the entire Arctic sector. Atlantic, Pacific and even the central Arctic sectors are showing large negative sea ice area anomalies.

While we use sea ice concentration data supplied by NASA via the National Snow and Ice Data Center (NSIDC), there are some differencesbetween the way we and NSIDC process our sea ice indices. NSIDC uses 10-day running means; we use 3-day running means. NSIDC will often report sea ice extent indices and records, we are reporting a new sea ice minima sea ice area. The ice area metric includes year-to-year variations within the central pack ice and not just variations in the southern sea ice edge. Regardless of these differences, the rapid rate of sea ice melt this summer, along with the current negative sea ice anomalies almost guarantees a record Northern Hemisphere summer sea ice minimum this summer, by any metric.